Word Study
teaspoonful
CIDE DICTIONARY
teaspoonful, n.
As much as teaspoon will hold; enough to fill a teaspoon. In cooking, it is usually estimated as 4.9 milliliters, which is t.
"In the 1890 dictionary, it was defined as a fluid dram or one quarter of a tablespoonful." [1913 Webster]
For further exploring for "teaspoonful" in Webster Dictionary Online